Cave diving

Cave diving is scuba diving which is done in underwater caves. Cave divers dive for adventure but also to find fossils and gather data (dirt samples, water temperature, etc.) that helps scientists better understand the earth and the environment.

Cave diving is more dangerous than diving in open water:

cave-ins can bury divers and drown them

divers can panic from being in a small, enclosed space (a panic which is called "claustrophobia")